Programa de Pós-Graduação em Química - PPGQ

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https://repositorio.ufcat.edu.br/handle/tede/29

Para o desenvolvimento, cultural, econômico e tecnológico de uma sociedade é preciso unir esforços em diferentes áreas do conhecimento através de ensino e pesquisa de qualidade, realizadas por profissionais críticos, capazes de entender as necessidades regionais, nacionais e ao mesmo tempo conjungando-as com as necessidades mundiais. Nesse contexto, as Instituições de Ensino Superior devem exercer o papel de preparar profissionais capazes de transformar, gerar, construir, sistematizar, inovar e socializar conhecimentos no sentido de promover desenvolvimento sustentável. Esses parâmetros, como é sabido de todos, só são alcançados com investimento forte em educação.

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Agora exibindo 1 - 11 de 11

Conjugação das técnicas de coagulação química (Moringa oleífera) e eletroquímica (DDB) no tratamento de efluente real de indústria de tintas
(Universidade Federal de Goiás, 2018-03-15) Barbosa, Andreia Daniane; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Andrade, Leonardo Santos; Sarmento, Antover Panazzolo; Barrado, Cristiano Morita
Treatment of a real paint industry wastewater using a natural chemical coagulant based on Moringa oleifera (MO) seeds associated with Ca 2+ salts (nitrate or chloride) in order to potentiate its coagulating effect. This method of treatment was combined with the electrochemical technique from the use of a boron doped diamond electrode in a flow reactor. The main purpose of the treatments investigated was to evaluate the possibility of reuse of treated water in the production of a new paint. The treatment of the residue was evaluated by its turbidity, DFZ (color), total solids content, chemical oxygen demand (COD), biotoxicity and microbiological tests. The optimum conditions for coagulation were obtained at pH 6.5 and with coagulant dosage (50 g/L of MO) of 80 mL for each 1.0 L of residue (80 mL/L). The optimum concentration of Ca 2+ incorporated into the coagulant was 0.125 mol/L. The viability of the treatment, evidenced by the reuse of the treated water for the production of a new paint (made by the company supplying the waste), showed compatible quality with the water used by the company (tap water) only when the treatment was carried out using MO aqueous extract in association with Ca(NO 3 ) 2 salt. For the electrochemical treatment, the limit current density of (35 mA/cm 2 ) and an electrolysis time of 90 min were used. Bio-toxicity assays (A. Salina) showed that the mortality of micro crustaceans was reduced from 100% (raw effluent) to only 11% and that 85% of the effluent organic load was eliminated at the end of the electrolysis process. In addition, microbiological assays showed that the amount of mesophiles decreased by more than six orders of magnitude and no thermotolerant coliform colony was formed.
Degradação do corante tartrazina utilizando o TiO2: Ce em um sistema conjugado dos processos eletroquímico/fotocatalítico
(Universidade Federal de Goiás, 2015-06-12) Souza, Cláudio Roberto de; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Godinho Júnior, Mário; http://lattes.cnpq.br/8364676654739392; Godinho Júnior, Mário; La Porta, Felipe de Almeida; Andrade, Leonardo Santos
The effects of inclusion of cerium ions on the photocatalytic activity of TiO2 were studied in this work, so that the tartrazine dye, a food dye belongs to the class of azo compounds, it was degraded. Characterization techniques such as X-ray diffraction (XRD), diffuse reflectance (UV-VIS) and scanning electron microscopy (SEM) were used to understand the relationship between structure and photocatalytic activity for the oxides synthesized by the method of polymeric precursors with different temperatures of calcination. According to the analysis by X-ray diffraction, the crystalline anatase phase was predominant on calcinations at temperatures equal to and less than 750 ° C for the synthesized compounds. Photocatalytic degradation of the dye Tartrazine, catalyzed by the synthesized compounds was evaluated and compared to P25 (trade photocatalyst) and undoped titanium oxide. Best performance was observed in the photocatalytic activity of P25, followed by titanium oxide doped cerium ten percent and finally the non-doped titanium oxide, respectively obtaining an elimination of 100% color; 45.92% and 33.89% in 60 min, 71.18% and reaching 57% at 120 min respectively for the titanium oxide doped with ten percent of cerium and titanium oxide undoped flow reactor. Thus it is clear that doping the material improved photocatalytic performance. For coupling techniques were performed in three electrolysis current density: 10; 30 and 50 mA / cm2, yielding an elimination of color respectively 26.25%; 37.94% to 40.67%, in this case, the process efficiency is not only related to color removal also depends on the energy consumption, which was 0.26 kWh / g; 0.88 kWh / g 1.85 kWh / g for current densities of 10; 30 and 50 mA / cm2, respectively, and the current density of 30 mA / cm2 showed the most money. Having optimized the two processes, one can then perform the photoelectrochemical experiments, whereas for all three catalysts studied, the combined processes (photoelectrochemical) performed better compared to the separate processes, respectively being obtained discoloration of 100%; 48.82% and 39.00% in 60 min, reaching 73.26% and 65.54% respectively for 120 min in titanium oxide doped with ten percent of cerium and titanium oxide undoped.
Desenvolvimento de métodos eletroquímicos para determinação de neurotransmissores utilizando eletrodos de zircônia nanoestruturada e diamante dopado com boro
(Universidade Federal de Goiás, 2014-01-28) Paranhos, Maysa de Melo; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Andrade, Leonardo Santos; Laurindo, Edison Aparecida; Figueiredo, Alberthmeiry Teixeira de
DSA® electrodes modified with films ErYZrO2 or YZrO2 and boron-doped diamond electrodes (BDD) were tested as electrochemical sensors detect front of the neurotransmitter epinephrine and its interfering ascorbic acid (AA) and uric acid (UA), which coexist with epinephrine in biological fluids and are also electroactive, rusting in the same potential that epinephrine. The physical and morphological characterization of the films of ZrO2 were performed using the techniques of XRD, SEM / FEG, EDXS and Open circuit potential. For electrochemical characterization of the sensor in developing were used the techniques of cyclic voltammetry (CV), differential pulse voltammetry (DPV) and Flow Injection Analysis with Amperometric Detection. The analyzes used for physical and morphological characterization of the ZrO2 films demonstrated that the technique of spin coating together with the methodology used for the deposition of ZrO2 films on the surface of substrate DSA® showed films were obtained satisfactory. The BDD electrodes showed good catalytic activity for both analyzed substances (EP, AA and UA). While BDD electrode showed good sensitivity for detection of EP in the presence of AA, electrodes ZrO2 addition to good sensitivity and selectivity showed good reproducibility for the detection of EP without interference from UA and AA.
Desenvolvimento de um aptassensor para detecção do vírus da dengue
(Universidade Federal de Goiás, 2017-08-17) Souza, Evellyn Gonçalves de; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Neves, Adriana Freitas; http://lattes.cnpq.br/2984939300978146; Neves, Adriana Freitas; Santos, Maria Rita de Cássia; Vieira, Pabline Marinho
Dengue is an endemic disease that causes wide concern both the health systems and to the patients. Thus, it is important that studies aiming at diagnoses faster and with possibility of field application can be developed for the medical intervention happens early, avoiding the worsening of the cases. Therefore, the aim of this work was to develop an electrochemical biosensor based on the use of aptamer as a bioelement for recognition on the surface of the boron doped diamond electrode (BDD) for the detection of each of the four serotypes of the dengue virus. Previously to the development of the biosensor, the dot-blot and apta-PCR techniques were used as validation methods for the interaction between aptamer B07 and target, the 5'UTR region present in the viral genome. The cyclic voltammetry technique was used in the analysis of redox reactions on the surface of the BDD electrode with and without modification of its surface with chitosan film. Ferrocene was used as the redox mediator and electroactive indicator of hybridization of the DNA strands formed in the sensor. The peaks of current indicated that the electrode with chitosan film modification on its surface presented greater stability. The redox compound had higher affinity for the double chains hybridized on the surface of the electrode, showing current values for DENV 1, 2, 3 and 4 of were 0.73; 0.69; 0.79 and 1.03 μA, respectively. These values were higher than the current found for the single-stranded aptamer (ssDNA), which was 0.62 μA, as well as for the current obtained from the aptamer hybridized with its complementary strand (dsDNA) whose value was 0.91 μA. Analyzes with time variations were performed showing a reduction in current values as a function of time, probably due to the reduction of the interaction of the electroactive material in the sensor. The aptasensor developed here showed good detection distinction between nucleic acid sequences, presenting potential for application in the detection of dengue virus.
Desenvolvimento de um método por ponto nuvem dos hormônios naturais E1 e E2 em amostras de urina e determinação por CLAE/EC utilizando eletrodo de diamante dopado com boro
(Universidade Federal de Goiás, 2015-08-06) Amorim, Kamila Pereira de; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Andrade, Leonardo Santos; Brocenschi, Ricardo Francisco; Alves, Vanessa Nunes
Cloud point extraction method (CPE) was used for the determination of estrone (E1) and 17β-estradiol (E2) hormones in human urine. The combination of the electrochemical detection techniques with high-performance liquid chromatography (HPLC-EC) was used for the detection and quantification of these hormones. A boron doped diamond electrode (BDD) pretreated cathodically was used as electrode material for all electrochemical measurements. The optimized chromatographic parameters resulted in a mobile phase composition of KH2PO4 (0.01 mol L-1; pH 5.0) / ACN (72:28 V/V), flow 1.2 ml min-1. An applied potential for electrochemical detection of 1.0 V x Ag/AgCl (3.0 mol L-1) was selected from hydrodynamic voltammograms constructed for each hormone changing the potential between 0.3 V and 1.2 V x Ag/AgCl (3.0 mol L-1). Limits of detection (S/N = 3) of 500 ng mL-1 and limits of quantification of 800 ng mL-1 were obtained for both E1 and E2 hormones without any extraction process. Urine samples at pH 5.0 and 7.0 were investigated aiming the influence of pH on the efficiency of the CPE process, and the optimum results for the most current signal of the hormones was obtained at pH 7.0. Extractor solvent volumes were changed in the 0.5-2.5 mL range, and the optimum results were obtained when using 1.0 mL of Tergitol TMN-6 surfactant (10% aqueous solution). From the equation of the calibration curves obtained with and without the CPE procedure it was possible to determine the pre-concentration factor (FC) and all the other parameters involving the efficiency of CPE method. A comparison of the efficiency of CPE method with direct liquid-liquid extraction with the organic solvent CCl4 was carried out and the results showed that the CPE method was quite superior to liquid-liquid extraction. The validation of the method was carried out from intra-day recovery experiments and inter-day and evaluated the accuracy, precision and repeatability. The proposed method was applied to individual samples of urine of 1 man, 1 pregnant woman, 1 woman in fertile age, and 1woman in lactating stage. The values of the variation coefficients of the recovery percentages were lower than 15%.
Determinação eletroquímica do agrotóxico tiabendazol extraído e pré-concentrado em amostras de tomate pela técnica de ponto nuvem usando eletrodo de diamante dopado com boro
(Universidade Federal de Goiás, 2019-03-29) Caixeta Neta, Antônia; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Andrade, Leonardo Santos; Alves, Vanessa Nunes; Muñoz, Rodrigo Alejandro Abarza
In Brazil, there is a significant consumption of tomatoes and, according to the report of the Program of Analysis of the Residues of Agrochemicals in Food (PARA) available by ANVISA, the tiabendazole (TBZ) fungicide was detected in some tomato samples analyzed. The detection of this substance is considered to be prohibited, since the TBZ is authorized only for application in seeds of the plant and, therefore, could not be found in fruits. Thus, electrochemical methods can be used for the determination of pesticides in complex samples and in low concentration levels, because they produce fast and reliable measurements, consuming small amounts of reagents. In this work, a procedure for the electroanalytical determination of TBZ fungicide in tomato fruits using boron-doped diamond electrode (BDD) was developed and validated using the cloud extraction and preconcentration (CPE) technique. The analytical technique used in this determination was the High Performance Liquid Chromatography coupled to an electrochemical detector (HPLC-EC), by the use of the BDD electrode. In order to evaluate the main variables of the CPE process, it was used a 24 complete factorial planning to optimize the parameters. The CPE optimized condition was achieved by the use of Tergitol (19% V/V), NaCl (0.83 g), ultrasonic stirring time of 15 min and temperature of 36 °C. Under these conditions, the preconcentration factor obtained was 5.7. The limits of detection and quantification obtained were 2.7 × 10-8 mol L-1 and 5.5 × 10-8 mol L-1 , respectively. The average recoveries obtained in 3 days were satisfactory, varying between 80.7% and 115.1%, which demonstrates the good accuracy of the developed method. In the application of the method in commercial tomatoes, TBZ was detected in one of the samples analyzed. The differential pulse voltammetry (DPV) technique was also investigated for the electroanalytical determination of TBZ fungicide in tomato fruit (extracted and pre-concentrated by CPE) using BDD electrode in order to increase the analytical frequency. The use of DPV technique increased the analytical frequency by approximately 90 times compared to the HPLC/EC technique.
Estudo da composição de material particulado e compostos orgânicos voláteis no ar em Catalão - GO
(Universidade Federal de Goiás, 2015-02-27) Santos, Rafaela Souza; Romualdo, Lincoln Lucilio; Romualdo , Lincoln Lucílio; Pozza, Simone Andréa; Andrade, Leonardo Santos
The issue of pollution is not new. The burning of biomass used for heat generation already was beginning to anthropogenic processes of air pollution. The pollutants are in the atmosphere in solid, liquid and gaseous state. The set of solid and liquid particles is called particulate matter (PM), and the other form the set of gaseous pollutants. The MP covers a range of 0.1-100 microns and varies greatly in size composition, emission sources and adverse effects on health. The gaseous compounds are formed mostly of volatile organic compounds (VOCs), which are organic compounds which are gaseous at room temperature. These pollutants can be emitted by natural and anthropogenic sources, among which stand out the combustion processes and soil dust resuspension by wind action. The city of Catalão - GO has grown greatly in recent years, mainly due to the arrival of mining in the city exploring the carbonatite complexes Catalão I and Catalão II. The aim of this study was to monitor the atmospheric air in a region of the city of Catalan through the sampling and analysis of PM and VOCs. Samples MP, which occurred every six days over a period of 24 hours, were carried out for TSP, PM10 and PM2,5 in HI-VOL samplers suitable for each particle size. Gravimetric analysis indicated that the measured concentrations are in accordance with the standards set by law. The elementary MP analysis was performed by EDXRF technique and indicated that the elements present are mostly from vehicle emissions and resuspended soil dust by the wind. Sampling was performed by VOCs microextraction technique of solid phase (SPME - solid phase microextraction) twice a week for 12 hours. The analysis of the sampled VOCs was performed by gas chromatography-mass spectrometry (GC / MS - gas chromatography mass spectrometry) in which the compounds were identified by comparison with a NIST library / MS (National Institute of Standards and Technology / Mass Spectral) present in the equipment. The identification of these compounds indicated a strong influence of vehicle emissions in the composition of atmospheric air.
Metodologias de preparo de amostras e quantificação de metais pesados em sedimentos do Ribeirão Samambaia, Catalão-GO, empregando Espectrometria de Absorção Atômica
(Universidade Federal de Goiás, 2014-01-27) Mesquita, Glenda Máris; Coelho, Luciana Melo; http://lattes.cnpq.br/0074807107314789; Coelho, Luciana Melo; Eiras, Sebastião de Paula; Andrade, Leonardo Santos
Ensuring water quantity and quality for all human beings has been a very discussed topic nowadays. The River Samambaia, watershed that supplies the city of Catalão, has been suffering with anthropogenic actions and the consequences of human intervention. To evaluate the quality of water may be used: water, particulates and sludge. The sediments can store dangerous substances and then can act as a secondary source of pollution by releasing contaminants into the aquatic environment. Within this context, the aim of this study was to evaluate the potential for contamination and the quality of the River Samambaia, located in Catalão-GO. For this, samples of water and sediment were collected at seven sampling sites along the river and the metals arsenic, cadmium, lead, chromium, manganese and nickel, which are considered toxic, were quantified. Was also performed, on the sampling sites, the analysis of physico-chemical water parameters: pH, conductivity, dissolved oxygen, temperature and salinity. For the extraction of metals fixed in the sediment samples was employed three methods of opening: ultrasound assisted extraction, digestion in digester block and microwave digestion. The quantification of metals was done by Atomic Absorption Spectrometry, by Flame or by Electrothermal Atomization in Graphite Furnace. The three methods opening samples used were effective, but the microwave digestion excelled in all cases. Among the physico-chemical parameters analyzed, pH showed values outside those permitted by law in all sampling points and dissolved oxygen showed the value below allowed only in point 7. In measurements of metals in water samples, cadmium, lead and chromium showed concentrations above the maximum allow by CONAMA. Already for the quantification of metals in the sediment samples, only chromium showed a concentration above the permitted limits. The results presented here indicate that human activities carried out in the river have contributed to adverse effects on local biota and humans.
Síntese e caracterização de óxido semicondutor a base de estanatos pelo método precursor polimérico
(Universidade Federal de Goiás, 2015-04-17) Bezerra, Marta Maria de Moura; Santos, Maria Rita de Cássia; http://lattes.cnpq.br/2598029192393541; Santos, Maria Rita de Cássia; Machado, Antônio Eduardo da Hora; Andrade, Leonardo Santos
In this work, the Praseodymium Stannate system was successfully synthesized by Polymeric Precursor Method. The crystallization temperature was evaluated by ATD and after calcination the material was characterized by XRD, spectroscopy in the infrared regions, spectroscopy in the region of UV-visible, scanning electron microscope(SEM) ,transmission electron microscope (TEM) equipped with an energy dispersive X-ray spectrometer (EDS) and photoluminescent measures. In the interests of possible applicability of semiconductor in catalysis were made trials in the discoloration of the tartrazine. The precursor powders calcined at different temperatures (400 ° C versus time (4, 8 and 12 hours) and 600, 800 and 1000 ° C for 4 hours) are single phase according to a results of X-ray diffraction. The degree of crystallinity increased with the temperature according to the results of the Crystallite Size and FWHM. The energy of the "bandgap" were calculated from the reflectance curves in the UV and showed obtaining a Semiconductor (~ 2.0 eV). By TEM was observed nanoscale particles monophasic with no secondary phase. The structure and morphology assessed by SEM showed an agglomerate and porous material. The optical property showed a possible applicability of the studied material as photoluminescent. According to the value of the "forbidden band" and the porosity of the materials, photocatalytic tests were carried out on discoloration of the dye tartrazine. The results showed that the studied material is promising for catalysis.
Tratamento de efluente real de indústria de tintas pelo uso de métodos conjugados de coagulação química e eletroquímico
(Universidade Federal de Goiás, 2016-03-09) Silva, Larissa Ferreira da; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Andrade, Leonardo Santos; Paula, Heber Martins de; Barrado, Cristiano Morita
In the last years problems regarding the availability and quality of water are gaining a lot of attention once the latest water crisis that occurred in Brazil were not restricted to arid and semiarid regions, but in regions with higher population density and industrial activity. Some types of industry activities have called more attention because its consume large volumes of water and contaminate lakes, rivers and groundwater. In this sense, the search for new wastewater treatments has become very promising, since this process can allows the reuse of the water and then reducing the consumption. The present work describes and discusses an investigation into the treatment of paint manufacturing wastewater (water-based acrylic texture) by coagulation (aluminum sulfate) coupled to electrochemical methods (BDD electrode). Two proposals are put forward, based on the results. The first proposal considers the feasibility of reusing wastewater treated by the methods separately and in combination, while the second examines the possibility of its disposal into water bodies. To this end, parameters such as toxicity, turbidity, color, organic load, dissolved aluminum, alkalinity, hardness and odor are evaluated. In addition, the proposal for water reuse is strengthened by the quality of the water-based paints produced using the wastewater treated by the two methods (combined and separate), which was evaluated based on the typical parameters for the quality control of these products. Under optimized conditions, the use of the chemical coagulation (12 mL/L of Al2(SO4)3 dosage) treatment, alone, proved the feasibility of reusing the treated wastewater in the paint manufacturing process. However, the use of the electrochemical method (i = 10 mA/cm2 and t = 90 min) was required to render the treated wastewater suitable for discharge into water bodies.
Tratamento de lixiviados de aterro sanitário combinando coagulação (sulfato de alumínio) e técnicas eletroquímicas (diamante dopado com boro)
(Universidade Federal de Goiás, 2019-03-08) Oliveira, Mayra Silva de; Andrade, Leonardo Santos; http://lattes.cnpq.br/5360511377400279; Andrade, Leonardo Santos; Sarmento, Antover Panazzolo; Santos, Maria Rita de Cássia
Landfill leachate contains a wide variety of organic and inorganic compounds that give the effluent high toxicity, high organic load and low biodegradability. Due to its complex composition, this effluent has acquired high research interest in the use and combination of new treatment technologies which can provide the balance of the environment. This study presents and discusses the results obtained in the treatment of raw landfill leachate with a combination of coagulation-flocculation and electrochemical techniques using a filter-press reactor with a boron-doped diamond electrode. The treatment success was demonstrated by the quality of treated water, which was evaluated based on parameters such as color, odor, turbidity, chemical oxygen demand, biochemical oxygen demand, free and total chlorine, total nitrite and nitrate, ammonia and microbiological tests (mesophiles and thermotolerant coliforms). The best conditions for coagulation-flocculation involved a dosage of 20 mL/L of Al2(SO4)3 at pH 6.0 followed by electrochemical treatment by 3 h. To reduce the energy consumption, the best condition for electrochemical treatment was performed by the application of different limiting current density step sequences, in the order to keep the applied current always closer to that in which the process is mostly controlled by diffusion (limiting current, Ilim). This strategy reduced the energy consumed in removing the organic load by up to 40% while maintaining a similar effective mineralization rate (> 90% removal) between stages. Microbiological tests revealed that the number of mesophiles was reduced by more than twelve orders of magnitude after electrolysis, indicating the important sanitizing effect caused by the HClO/chloramine species generated in the process. The parameters color, turbidity and ammoniacal nitrogen were completely eliminated from the treated landfill leachate at the end of the electrolysis process.

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